The method you want, is to use a single storage set with specific options selected. You should configure Retrospect to do a normal backup to the same storage set every time. Also you should not choose the "Don't match duplicates" option (this is selected by default, be sure to deselect it).
Here are the steps used in an example:
1. Create new script for backing up one file.
2. Run backup the first time. Check the log, the file was backed up.
3. Immediately run backup again and check the log. Since there are no changes, the file was not backed up.
4. Edit the script's options. Select, More Options. Select, Matching. Turn off Don't add duplicates to storage set.
5. Immediately run backup again. Notice the file was backed up, even though no changes were made to the file.
Below is a sample log file:
* Retrospect version Apple Servers 2.0Ci A/UX
launch at 7/11/95 6:19 PM
+ Normal Backup using <support> duplicate backup at 7/11/95 6:51 PM
To StorageSet <support>
- 7/11/95 6:51:01 PM: Copying Guest
7/11/95 6:51:10 PM: Comparing Guest
7/11/95 6:51:11 PM: Execution completed successfully
Completed: 6 files, 7 KB
Performance: 0.1 MB/minute (0.1 copy, 0.4 compare)
Duration: 00:00:10
+ Normal Backup using <support> duplicate backup at 7/11/95 6:51 PM
To StorageSet <support>
- 7/11/95 6:51:28 PM: Copying Guest
7/11/95 6:51:28 PM: no files need to be copied
7/11/95 6:51:36 PM: Execution completed successfully
Duration: 00:00:07
+ Normal Backup using <support> duplicate backup at 7/11/95 6:52 PM
To StorageSet <support>
- 7/11/95 6:52:27 PM: Copying Guest
7/11/95 6:52:35 PM: Comparing Guest
7/11/95 6:52:36 PM: Execution completed successfully
Completed: 6 files, 7 KB
Performance: 0.1 MB/minute (0.1 copy, 0.4 compare)
Duration: 00:00:09